1. Field
The present disclosure relates to swiveling chairs that include electrically wired devices above the swivel.
2. Description of Related Art
Swiveling chairs may be constructed using a pedestal or legged base supporting a chair seat, and a mechanical swivel, such as a ball bearing, interposed between the seat and the base. A ball bearing swivel may be disposed horizontally between the base and the seat, and bear the weight of the seat and its occupant through the balls and races of the ball bearing. Ball bearings provide a smooth, quiet, and nearly frictionless swiveling action, relative to other bearing types. In such chairs, the ball bearing swivel provides the only practical structure for attaching the seat to the base. As such, the swivel must also carry a tension load to prevent separation of the chair from the base. Separation loads typically vary periodically between zero and peak values as occupants of the chair do not sit perfectly still but instead shift their center of gravity away from the load center of the swivel.
Accordingly, ball bearings used in swivel chairs should be capable of bearing varying tension and thrust loads while swiveling. Certain bearing types, such as precision tapered roller bearings, are designed for bearing axial loads in thrust and can be modified to carry significant tension loads, but are prohibitively expensive for most chair applications. A more cost-effective ball bearing used in many swiveling chairs comprises upper and lower stamped metal plates that fit together to provide a race for steel balls set therein. The plates are axially fastened by a centrally-disposed tension fastener, such as a pin, rivet, or bolt, which bears the tension loads imposed on the swivel by use of the chair and serves as a pivot for the swivel assembly.
The centrally-disposed tension fastener and adjoining two plates form a critical structural part of such swiveling chair assemblies. This part needs to have adequate strength and fracture toughness to last the expected life of the chair without failure, while imparting a feeling of solidity to the chair seat. This is particularly important for seats that include high seat backs, which enhance user comfort but also add a lever arm that can greatly increase tension stress on the swivel when the user leans back. Therefore it is particularly important to provide a robust, yet cost-effective swivel mechanism for high-backed swiveling chairs.
Chairs of both the swiveling and static variety have been provided with wired electrical devices in the seat structure. For example, seats have been wired with audio speakers or with motors for massage devices or other applications. In a static chair, wires can simply be passed through the column pedestal base of the chair into the seat upholstery and routed to the electrical device. In a swiveling chair, an electrical conductor must somehow bridge the swiveling mechanical connection between the base and seat. One solution to this problem is to route a wire from the chair base beyond the outer perimeter of the swivel mechanism and into the upholstery of the chair seat. However, such routing may result in exposing the wire outside of the chair envelope, which is esthetically unattractive. Such routing may also subject the wire to frequent flexure, or to risks of being snagged or cut, which is functionally undesirable. It would be therefore desirable to provide a wired swiveling chair without these and other disadvantages of currently available designs.